High interannual variability of a climate-driven amphibian community in a seasonal rainforest

Abstract

Seasonality exerts strong pressures on biodiversity patterns. Yet, temporal beta-diversity is poorly studied in tropical systems, and the drivers of variability in amphibian activity and seasonality remain largely unknown. We quantified intra-and interannual variation in temporal beta-diversity relying on a nine-year, year-round survey (51 species, n > 23 000) performed in a protected area (Betampona, Madagascar). We assessed the dependence on climate of beta-diversity and abundance using a distance-based redundancy analysis and generalised linear mixed models, respectively. Despite the majority of species being preferentially active during one specific period, beta-diversity and abundance were more variable between years than within years. Temporal variation in beta-diversity was best explained by temperature (but climate accounted for only 2% of variation). Species abundance was best explained by temperature (for 32% of the tested species), monthly humidity (30%) and monthly rainfall (24%). We found no climatic dependence for 24% of the species. Our results suggest that studies focusing on species phenology can be misleading when based on single-year surveys even in seasonal systems. The high interannual variability in diversity may be due to an adaptive responses to an important regime of stochastic events. Given the direction of the relationships between weather and abundances, we predict that a large proportion of amphibians would suffer from climate change in Madagascar. We emphasise the need to account for multiple temporal scales in studies of tropical species composition and abundance to better understand species phenology and their response to climate change, and make targeted conservation actions more effective.

Drivers of assemblage‐wide calling activity in tropical anurans and the role of temporal resolution

“…Chorusing formation may benefit calling energetic costs by increasing attractiveness for mates to a common breeding site and minimizing predation risk (Schwartz & Bee, 2013). Although chorusing attendance and diel activity patterns are widely described in species‐specific studies (Bertoluci & Rodrigues, 2002; Gottsberger & Gruber, 2004; Heinermann et al., 2015; Lopez et al, 2011; Schalk & Saenz, 2016), community‐wide approaches remained elusive (Dubos et al., 2020; Guerra et al., 2020; Ulloa et al., 2019). Considering our findings on the influence of habitat heterogeneity and species interactions on nightly compositional variation of anuran assemblages, we argue that future studies should take into consideration the contribution of ecological contexts in species calling activity, in addition to abiotic factors such as temperature and rainfall.…”

“…Chorusing formation may benefit calling energetic costs by increasing attractiveness for mates to a common breeding site and minimizing predation risk (Schwartz & Bee, 2013). Although chorusing attendance and diel activity patterns are widely described in species-specific studies (Bertoluci & Rodrigues, 2002;Gottsberger & Gruber, 2004;Heinermann et al, 2015;Lopez et al, 2011;Schalk & Saenz, 2016), community-wide approaches remained elusive (Dubos et al, 2020;Guerra et al, 2020;Ulloa et al, 2019). signalling parameters or behaviour when exposed to heterospecific calls (Both & Grant, 2012;Phelps et al, 2006), while the influence of species interactions on calling activity still remains to be elucidated.…”

“…Therefore, understanding how communities vary in time (i.e. temporal beta‐diversity; Baselga et al., 2015; Legendre & Gauthier, 2014) and the drivers of community‐wide activity can shed light on the contribution of short‐term dynamics of ecological communities to the underlying processes across scales (Dubos et al., 2020).…”

“…by maintaining low levels of desiccation in forested patches) and dispersal dynamics underlying variation in the composition of assemblages (Signorelli et al., 2016; Werner et al., 2007). Nonetheless, short‐term variation in species activity has been mainly addressed with respect to meteorological and social factors (Dubos et al., 2020; Guerra et al., 2020; Llusia et al., 2013; Oseen & Wassersug, 2002; Saenz et al., 2006; Schalk & Saenz, 2016) and the role of ecological processes driving such dynamics remain largely unexplored.…”

“…Nonetheless, short-term variation in species activity has been mainly addressed with respect to meteorological and social factors (Dubos et al, 2020;Guerra et al, 2020;Llusia et al, 2013;Oseen & Wassersug, 2002;Saenz et al, 2006;Schalk & Saenz, 2016) This knowledge gap can be traced back to historically challenging conditions in addressing nocturnal phenomena (Gaston, 2019), in addition to the human-observer limitation in investigating multiple sites simultaneously. Currently, modern techniques enabling passive acquisition of high-resolution data have been solving these practical issues and steadily improving our capacity to address diverse ecological phenomena (Gaston, 2019;Rocchini et al, 2016).…”